In the presence of a magnetic field the quasi-continous levels of simple energy bands are coalesced into one-dimensional sub-bands and the "time reversal" degeneracy of the levels is split. The energy levels are characterized by the quantum numbers: ℏkH, the crystal momentum along the magnetic field direction; l, the Landau magnetic quantum number; and M, the component of the total angular momentum along the magnetic field which is characteristic of the atomic states in the tight-binding limit. In the case of degenerate valence bands, the effect of a magnetic field is complicated by degeneracy effects and the levels in a magnetic field are characterized by two or more pairs of (l, M) values. The selection rules, polarization effects, and the character of the absorption spectra for interband transitions in the presence of a magnetic field are discussed and illustrated by experimental data for Ge and InSb. A discussion of practical and experimental considerations of Zeeman-type interband magneto-optical effects is also presented.